Large area deployable spacecraft antenna

ABSTRACT

A large area deployable antenna for a spacecraft to be enclosed in a cylindrical shroud during launch. The antenna includes a reflector having a number of panels hinged edge-to-edge on hinge axes parallel to the central axis of the spacecraft body and mounting antenna elements, such as collapsible phased array elements and means for mounting at least one of the central reflector panels on the spacecraft body and for folding of the remaining panels into a stowed configuration, wherein the several panels are symmetrically arranged about the body within an envelope slightly smaller than the interior of the spacecraft shroud, and a deployed configuration, wherein the panels are located substantially in a common plane to form an antenna array which is symmetrical relative to a plane normal to the deployed reflector and containing the spacecraft body axis. The panels are releasably secured in stowed configuration during launch and unfolded to deployed configuration by spring action in orbit.

United States Patent Hall et al.

1541. LARGE AREA DEPLOYABLE SPACECRAFT ANTENNA [72] Inventors: CharlesH. Hall, Redondo Beach; Albert L. Young, Cypress; N. Keith Young,Torrance, all of Calif.

[73] Assignee: TRW Inc., Redondo Beach, Calif.

[22] Filed: June 25, 1970 I [21] Appl. No.: 49,611

[451 Oct. 17, 1972 Primary Examiner-Eli Lieberman Attorney-Daniel T.Anderson, Donald R. Nyhagen and Jerry A. Dinardo 57 ABSTRACT A largearea deployable antenna for a spacecraft to be enclosed in a cylindricalshroud during launch. The antenna includes a reflector having a numberof panels hinged edge-tmedge on hinge axes parallel to the central axisof the spacecraft body and mounting antenna elements, such ascollapsible phased array elements and means for mounting at least one ofthe central reflector panels on the spacecraft body and for folding ofthe remaining panels into a stowed configuration, wherein the severalpanels are symmetrically arranged about the body within an envelopeslightly smaller than the interior of the spacecraft shroud, and adeployed configuration, wherein the panels are located substantially ina common plane to form an antenna array which is symmetrical relative toa plane normal to the deployed reflector and containing the spacecraftbody axis. The panels are releasably secured in stowed configurationduring launch and unfolded to deployed configuration by spring action inorbit.

11 Claims, 12 Drawing Figures a r/Mg Pmm cmm 3.699.581

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BACKGROUND OF THE INVENTION 1 Field of the Invention This inventionrelates generally to antennas and more particularly to a large areadeployable antenna for spacecraft.

2. Prior Art Spacecraft communication systems vary widely in design,purpose, and the types of antenna they employ. In many cases, the designof the communication antenna constitutes a major portion of the overallsystem design effort. This is true, for example, of the antenna for asynchronous communications satellite which is required to communicatesimultaneously with two loworbit space vehicles.

From the operational standpoint the preferred communication system forsuch a satellite is a phased array system. As is well-known to thoseversed in the art, such a phased array communication system employs aphased array antenna including a large area reflector mounting an arrayof antenna elements, and a means for electronically actuating theelements in such a way as to steer the antenna radiation beam through arelatively large angle without any physical motion of the antennastructure. In the synchronous communication satellite system referred toabove, for example, the satellite mounts a phased array antenna whoseantenna elements are electronically actuated in such a way as tocommunicate with one low orbit space vehicle during one half of thecycle and with the other space vehicle during the other half of thecycle.

There have been a number of investigations directed toward theapplication of phased arrays to satellite communication systems.However, these investigations have paid little attention to theconfiguration analysis of the phased arrays in relation to thesatellite. Also, designing a phased array of low structural weight,which can be stowed for launch and reliably deployed in orbit, presentsa complex design problem which is not satisfactorily solved by thephased array configurations proposed thus far. Particularly, it is amajor task to unfurl or deploy a large antenna array while at the sametime holding the tolerances within the limits required for a phasedarray communication system.

SUMMARY OF THE INVENTION The present invention provides an improvedlarge area deployable spacecraft antenna which is primarily designed forthe use discussed above, i.e., as a phased array antenna for asynchronous communication satellite capable of communicatingsimultaneously with two low orbit space vehicles. The antenna has alarge area reflector comprising a group of panels hinged edge-toedge onhinge axes parallel to the longitudinal axis of the spacecraft body.These reflector panels have outer sides mounting antenna elements. Atleast one central panel of the reflector is attached to the spacecraftbody in a manner such that the reflector panels are foldable betweenstowed and deployed configurations. In stowed configuration, the panelsare generally symmetrically arranged about the spacecraft body within anenvelope smaller than the interior of the shroud which encloses thespacecraft during launch, thus to permit containment within the shroudof the entire spacecraft structure including the spacecraft body and itsstowed antenna. In their deployed configuration, the reflector panelsare located in a common plane generally parallel to the spacecraft bodyaxis with the outer sides of the panels facing away from the spacecraftto form a spacecraft antenna.

In the particular inventive embodiment selected for discussion in thepresent disclosure, the antenna elements on the outer side of thereflector panels are phased array elements, such that the deployedantenna provides a phased array antenna. These antenna elements arecollapsible elements, such as compressible or deployable helixes, whichcollapse when the antenna is folded to its stowed configuration andextended to operating position when the antenna is deployed.

The present deployable antenna is equipped with locking means forreleasably securing the reflector panels in their stowed configurationand with deployment means for unfolding or unfurling the panels to theirdeployed configuration upon release of the locking means. The "disclosedlocking means are explosive fasteners, and the deployment means aresprings which act between the adjacent reflector panels to rotate thelatter to their deployed configuration when the explosive fasteners aredetonated to release the panels for deployment. Dampers may be providedfor cushioning the panels upon arrival in their deployed positions.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a side elevation of a spacecraft installed within the shroudof a launch vehicle and mounting a deployable antenna structureaccording to the invention, the antenna being shown in its stowedconfiguration;

FIG. 2 is an enlarged section taken on line 2-2 in FIG. 1;

FIG. 3 is an enlarged section taken on line 3-3 in FIG. 1;

FIG. 4 is an enlarged section taken on line 4-4 in FIG. 1;

FIG. 5-is a partial section of the area enclosed by the circular arrow 5in FIG. 4;

FIG. 6 illustrates the spacecraft in orbit with the antenna structuredeployed;

FIG. 6a is an enlargement of the area enclosed by the arrow 6a in FIG.6;

FIG. 6b is an enlarged detail of one antenna element;

FIG. 7 is a section through the spacecraft illustrating the antennastructure in its stowed and deployed configurations with parts of thespacecraft omitted for the sake of clarity; and

FIGS. 8 through 10 illustrate modified deployable antenna structuresaccording to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 through 7 illustrate aspacecraft 10 including a large area deployable antenna 12 according tothe invention. In FIG. 1, the spacecraft is shown mated to a launchvehicle 14 for launching the spacecraft into orbit. This launch vehicleincludes a lower booster 16, an interstage burner 18, and a cylindricalshroud 20 which surrounds the spacecraft during launch. After launch theshround 20 is jettisoned and the interstage burner 18 is fired toseparate the spacecraft from the booster and place the spacecraft infinal orbit. The burner is then separated from the spacecraft.

The illustrated spacecraft 10, which is a synchronous communicationsatellite of the kind referred to earlier, has a body including an opentubular frame 24 of hourglass configuration. This frame mounts a centralequipment compartment 26. Frame 24 includes a pair of relatively largediameter coaxial end rings 28 joined to the equipment compartment 26 bytubular frame members 30. At the frame ends are deployable solar arrays32 shown in FIG. 6. These solar arrays form no part of the presentinvention and hence need no further explanation.

The illustrated deployable antenna 12 is a phased array antennaincluding a rectangular radiation reflector 34 shown in FIG. 6comprising a group of panels 36. These reflectors are joinededge-to-edge by hinge connections 38 having hinged axes parallel to thecentral axis of the spacecraft 10. In the particular inventiveembodiment illustrated, the antenna reflector 34 contains an odd numberof panels 36 and hence one central panel. The central panel isdesignated by the reference character C. The center reflector panel C isrigidly attached to the spacecraft frame 24 by struts 40 in such a waythat the panel is generally tangentially disposed relative to the frameend rings 28. Mounted on the outer sides of the reflector panel 36 arecollapsible antenna elements 42 arranged in the manner of a phasedarray.

Reflector panels 36 are foldable at the hinges 38 between their stowedor launch configuration in FIG. 1 and their deployed configuration ofFIGS. 6 and 7. In their stowed configuration, the reflector panels aregenerally symmetrically arranged in a polygonal configuration about thespacecraft 10. In their deployed configuration, the panels are arrangedin a common plane to form a-phased array antenna 44. The common plane ofthe reflector panels 46 in their deployed configuration may be either aflat plane or a curved plane, depending upon the desired radiationpattern of the antenna.

As shown in the drawings, the fully deployed reflector 34 is symmetricalabout a plane P, normal to the reflector and containing the central axisof the spacecraft 10. This plane of symmetry intersects the center panelC of the reflector along its longitudinal center line and bisects thereflector 34.

In its stowed configuration, the illustrated radiation reflector 34conforms to a polygonal configuration having an even number of sides,specifically eight sides. Accordingly, the several sides of thepolygonal configuration, which are provided by the reflector panels 36,are arranged in pairs of parallel diametrically opposed sides. In orderto achieve both the above-mentioned symmetrical disposition of the fullydeployed reflector relative to the normal plane I, of symmetry and theeven sided polygonal configuration of the stowed reflector, all of thereflector panels 36 of FIG. 7, except the two outer end panels E, have auniform width, and these two end panels have a width half of that of theuniform width panels. When the reflector 36 occupies its polygonalstowed configuration, these two end panels are located diametricallyopposite and in a common plane parallel to the fixed center panel C, soas to form one side of the polygonal stowed configuration. The outerlongitudinal edges of these end panels are disposed adjacent one anotherapproximately in the plane P, of symmetry of the fully deployedreflector 36.

The lateral width of the reflector panels 36 and the projection of thecollapsed antenna elements 42 beyond the panels are dictated by theinternal diameter of the launch vehicle shroud 20 which surrounds thespacecraft 10 during launch. Thus, the panels and the collapsed antennaelements are so dimensioned that the antenna 12, in stowedconfiguration, is contained within a cylindrical envelope 2 smaller thanthe interior of the shroud. The illustrated antenna elements compriseinflatable plastic tubes (FIG. 6b). Secured to the wall of each antennatube is a helically wound wire 42a which constitutes the actual antennaradiating and receiving element. The antenna tubes are deflated andcollapsed to their broken line positions during launch and are extendedto their solid line operating positions in orbit through pressuringlines 421) from a gas pressure source (not shown) in each panelactivated by ground command signals.

Antenna 12 is equipped with locking means 46 for releasably locking theantenna panels 36 in their folded position and deployment means 48 forunfolding the panels to their deployed positions upon release of thelocking. The illustrated locking means 46 comprises a clip 51a whichjoins the outer edges of the adjacent end panels E in their deployedposition. Under this clip is a mild detonating fuse 51b which is ignitedby a ground command signal to separate the clip from the end panels andthereby release the antenna for deployment under the action ofdeployment means 48. The stowed end panels are retained in alignment bypins 51c (only one shown) each having a fuse 51d which is ignited withthe fastener fuse 51b to retract the pin. Deployment means 48 comprisetorsion springs 52 embodied in the hinge connections 38 and activebetween the adjacent reflector panels 36. These springs are stressedwhen the panels are folded to their stowed configuration and bias thepanels to their deployed configuration upon release of the locking means50. As shown in FIG. 5 the edges of the adjacent panels abut in theirfully deployed positions limit unfolding of the panels to thesepositions. If desired, damper cylinder (not shown) may be provided forcontrolling the deployment rate of the antenna in order to preventimpact of the adjacent panels at full deployment.

FIGS. 8 through 10 illustrate various alternative deployable antennaarrangements according to the invention. In FIG. 8, the antennareflector 34a has an even number, i.e., four of panels 36a arranged inpairs at opposite sides of the spacecraft equipment compartment 26. Thetwo panels of each pair are joined edgeto-edge by the hinge connection38a. One panel of each pair is joined to the equipment compartment 36 byhinge connection 39a adjacent and parallel to the outer edge of thepanel in a manner such that the panels are foldable between their solidline'stowed configuration and broken line deployed configuration of FIG.8. In their stowed configuration, the reflector panels are folded intoparallel face-to-face relation against opposite sides of the equipmentcompartment 26. In deployed configuration, the reflector panels aredisposed in a common plane to form a phased array antenna 12aessentially identical to antenna 44, except for the number of panels. Inthis regard, it is significant to note that the hinge connection 39abetween the equipment compartment 26 and the adjacent inner reflectorpanels 36a are spaced from the adjacentpanel edges distances equal tothose between the latterhinge connection and the plane P, of symmetry ofthe deployed antenna. During deployment, the edges of the inner panelsrotate to positions adjacent one another substantially within the planeof symmetry, as shown.

The modified antenna structure 12a, like the earlier described antennastructure, uses explosive locking means 50 to secure the reflectorpanels in their stowed configuration and torsion springs in the hinges38a to deploy the panels when the panels are released by detonation ofthe locking means.

As shown, the antenna elements 42a are mounted on the sides of thereflector panels 36a which face one another in the stowed positions ofthe panels. These antenna elements are collapsible elements, like thoseof the antenna 12, such that the elements may be collapsed when theantenna is folded and extended when the antenna is deployed.

FIGS. 9 and 10 illustrate deployable antennas 12b, 12c according to theinvention having radiation reflectors 34b, 34c with three and fivepanels, respectivelyJn each case, the center panel is rigidly mounted onthe spacecraft body frame. The adjacent panels of each reflector arejoined edge-to-edge by hinge connections for folding between theirillustrated solid line stowed configuration and their broken linedeployed configuration. The stowed configuration of each antenna is apolygonal configuration, that of FIG. 9 being a triangular configurationand that of FIG. 10 being a pentagonal configuration. In bothillustrated embodiments, the outer edges of the end reflector panels aredisposed adjacent one another approximately in the plane P, of symmetryof the antenna in its deployed configuration. These panel edges arejoined by explosive locking means 50b, 50c which releasably retain thereflector panels are connected by springs which unfold the panels totheir deployed configuration when the explosive locking means aredetonated, all in the same manner as described earlier in connectionwith FIGS. 1 through 7.

It will be understood that in each of the embodiments of FIGS. 8 through10, the spacecraft body is shaped to accommodate the antenna in itsfolded configuration and unfolding of the antenna to its deployedconfiguration.

What is claimed as new in support of letters patent is:

1. A spacecraft to be launched into orbit on a launch vehicle includingan outer shroud for surrounding said spacecraft during launchcomprising:

a spacecraft body; and

a large area deployable panel structure on said body comprising a numberof panels disposed edge-toe'dge with their adjacent edges parallel tothe longitudinal axis of said body, and including a central panel, hingemeans joining the adjacent panels along their adjacent edges, meansrigidly mounting said central panel on said body for folding of theremaining panels between a stowed configuration,

wherein said panels are generally symmetrically arranged in a polygonalconfiguration about said body within an envelope smaller than theinterior of said shroud and a deployed configuration, wherein saidpanels are disposed substantially within a commonplane, releasablelocking means for releasably securing said panels in their stowedconfiguration, and deployment means for unfolding said panels to theirdeployed configuration upon release of said locking means.

2. A spacecraft according to claim 1 wherein:

said panel structure in its deployed configuration is approximatelybisected by a plane containing the spacecraft body axis and intersectingsaid structure at right angles whereby the deployed reflector isgenerally symmetrically disposed relative to said latter plane.

3. A spacecraft according to claim 1 wherein:

said deployment means comprise springs acting between, the adjacentmutually hinged panels.

4. A spacecraft according to claim 2 wherein:

said polygonal stowed configuration has an odd number of sides, suchthat the two end panels of said panel structure when stowed are disposedat an oblique angle with their outer edges located substantially in saidplane of symmetry so as to define one apex of said polygonal stowedconfiguration, and said locking means releasably joins said end paneledges.

5. A spacecraft according to claim 2 wherein:

said polygonal stowed configuration has an even number of sides, and thetwo end panels of said panel structure have a lateral width equal toonehalf the lateral width of the remaining panels, such that in saidstowed configuration said end panels are disposed in the common planeparallel to said center panel with the outer edges of said end panelslocated substantially in said plane of symmetry to define one side ofsaid polygonal configuration; and

said locking means releasably joins said end panel edges.

6. A spacecraft to be launched into orbit on a launch vehicle includingan outer shroud for surrounding said spacecraft during launchcomprising:

a spacecraft body;

a large area deployable panel structure on said body comprising fourpanels including two center panels and two outer panels, each centerpanel and its adjacent outer panel constituting a panel pair, a hingeconnection joining the two panels of each pair in edge-to-edge relationon a hinge axis extending parallel the spacecraft body axis meansmounting said panels on said body for folding of said panels between astowed configuration, wherein said panels are generally symmetricallyarranged relative to said body within an envelope smaller than theinterior of said shroud and a deployed configuration, wherein saidpanels are disposed substantially within a common plane, releasablelocking means for releasably securing said panels in their stowedconfiguration, and deployment means for unfolding said panels to theirdeployed configuration upon release of said locking means; and

said mounting means comprising hinge connections joining said two centerpanels to said spacecraft body for rotation on hinge axes parallel tosaid spacecraft body axis and spaced from the outer hinged connectionsjoining said panels edge-toedge on parallel hinge axes;

said panels being foldable between a polygonal stowed configurationwherein said panels define edges of said two center panels in a ma nersu h the sides of a polygon and the outer edges of said that in saiddeployed configuration, said outer e Panels are disposed approximatelyin a plane edges of said center panels are disposed adjacent normal toand bisecting Said Center Panel and one another, and in said stowedconfiguration, the taining the axis of Said P yg and a p y panels ofsaid panel pairs are disposed in confrontconfiguration, wherein Saidpanels are disposed ing face-to-face relation at opposite sides of said10 Substantially in acommon Plane; spa ft b antenna means mounted on theouter sides of said 7. A spacecraft to be launched into orbit on a spacePanels;

vehicle including an outer shroud for surrounding said means for "gmoummg said center panel on the spacecraft during launch, comprising:body of Sald sPacecrafti a Spacecraft body; and releasable locking meansfor releasably oining sa d a deployable phased array antenna structureon said end panel edges m the stowed configuranon of Sam body comprisinga radiation reflector including a panels; and number of panels, hingedconnections joining said deployment means for ,mfoldmg Sald panels topanels edge-to-edge on hinge axes parallel to the dePIPYed configuranonupon release of sand longitudinal axis of said spacecraft body, meanslockmg means mounting said panels on said body for folding of zf antennastructure accordmg to Clam] 8 Said Panels between a stowedConfiguration, said antenna means comprise phased array antenna whereinsaid panels are generally symmetrically elements; arranged relative toSaid y Within an envelope said locking means comprise explosive lockingsmaller than the interior of said shroud, and a means;and

deployed configuration, wherein said panels are disposed substantiallyin a common plane and said reflector is approximately bisected by aplane containing said spacecraft body axis and intersecting the deployedreflector at right angles, whereby said reflector is generallysymmetrically disposed relative to said latter plane, explosive lockingmeans for releasably securing said panels in their stowed configuration,and springs acting between the adjacent mutually hinged panels forunfolding said panels to their deployed configuration upon release ofsaid locking means.

8. A deployable antenna structure for a spacecraft to be launched intoorbit on a launch vehicle having an outer shroud for surrounding saidspacecraft during launch Said antenna Structure comprising; confguration of said panels so as to form one side a radiation reflectorcomprising a number of panels ofsald polygon including a center paneland end panels, and

said deployment means comprise springs acting between the adjacentreflector panels.

10. An antenna structure according to claim 8 wherein:

said polygon has an odd number of sides; and

said end panels are disposed at an oblique angle to one another directlyopposite said center panels in said stowed configuration of said panelsto form one apex of said polygon.

1 1. An antenna according to claim 8 wherein:

said polygon has an even number of sides;

each end panel has one-half the lateral width of the remaining panelsand said end panels are disposed directly opposite said center panel ina common plane parallel to said center panel in said stowed

1. A spacecraft to be launched into orbit on a launch vehicle includingan outer shroud for surrounding said spacecraft during launchcomprising: a spacecraft body; and a large area deployable panelstructure on said body comprising a number of panels disposededge-to-edge with their adjacent edges parallel to the longitudinal axisof said body, and including a central panel, hinge means joining theadjacent panels along their adjacent edges, means rigidly mounting saidcentral panel on said body for folding of the remaining panels between astowed configuration, wherein said panels are generally symmetricallyarranged in a polygonal configuration about said body within an envelopesmaller than the interior of said shroud and a deployed configuration,wherein said panels are disposed substantially within a common plane,releasable locking means for releasably securing said panels in theirstowed configuration, and deployment means for unfolding said panels totheir deployed configuration upon release of said locking means.
 2. Aspacecraft according to claim 1 wherein: said panel structure in itsdeployed configuration is approximately bisected by a plane containingthe spacecraft body axis and intersecting said structure at right angleswhereby the deployed reflector is generally symmetrically disposedrelative to said latter plane.
 3. A spacecraft according to claim 1wherein: said deployment means comprise springs acting between theadjacent mutually hinged panels.
 4. A spacecraft according to claim 2wherein: said polygonal stowed configuration has an odd number of sides,such that the two end panels of said panel structure when stowed aredisposed at an oblique angle with their outer edges locatedsubstantially in said plane of symmetry so as to define one apex of saidpolygonal stowed configuration, and said locking means releasably joinssaid end panel edges.
 5. A spacecraft according to claim 2 wherein: saidpolygonal stowed configuration has an even number of sides, and the twoend panels of said panel structure have a lateral width equal toone-half the lateral width of the remaining panels, such that in saidstowed configuration said end panels are disposed in the common planeparallel to said center panel with the outer edges of said end panelslocated substantially in said plane of symmetry to define one side ofsaid polygonal configuration; and said locking means releasably joinssaid end panel edges.
 6. A spacecraft to be launched into orbit On alaunch vehicle including an outer shroud for surrounding said spacecraftduring launch comprising: a spacecraft body; a large area deployablepanel structure on said body comprising four panels including two centerpanels and two outer panels, each center panel and its adjacent outerpanel constituting a panel pair, a hinge connection joining the twopanels of each pair in edge-to-edge relation on a hinge axis extendingparallel the spacecraft body axis means mounting said panels on saidbody for folding of said panels between a stowed configuration, whereinsaid panels are generally symmetrically arranged relative to said bodywithin an envelope smaller than the interior of said shroud and adeployed configuration, wherein said panels are disposed substantiallywithin a common plane, releasable locking means for releasably securingsaid panels in their stowed configuration, and deployment means forunfolding said panels to their deployed configuration upon release ofsaid locking means; and said mounting means comprising hinge connectionsjoining said two center panels to said spacecraft body for rotation onhinge axes parallel to said spacecraft body axis and spaced from theouter edges of said two center panels in a manner such that in saiddeployed configuration, said outer edges of said center panels aredisposed adjacent one another, and in said stowed configuration, thepanels of said panel pairs are disposed in confronting face-to-facerelation at opposite sides of said spacecraft body.
 7. A spacecraft tobe launched into orbit on a space vehicle including an outer shroud forsurrounding said spacecraft during launch, comprising: a spacecraftbody; and a deployable phased array antenna structure on said bodycomprising a radiation reflector including a number of panels, hingedconnections joining said panels edge-to-edge on hinge axes parallel tothe longitudinal axis of said spacecraft body, means mounting saidpanels on said body for folding of said panels between a stowedconfiguration, wherein said panels are generally symmetrically arrangedrelative to said body within an envelope smaller than the interior ofsaid shroud, and a deployed configuration, wherein said panels aredisposed substantially in a common plane and said reflector isapproximately bisected by a plane containing said spacecraft body axisand intersecting the deployed reflector at right angles, whereby saidreflector is generally symmetrically disposed relative to said latterplane, explosive locking means for releasably securing said panels intheir stowed configuration, and springs acting between the adjacentmutually hinged panels for unfolding said panels to their deployedconfiguration upon release of said locking means.
 8. A deployableantenna structure for a spacecraft to be launched into orbit on a launchvehicle having an outer shroud for surrounding said spacecraft duringlaunch, said antenna structure comprising: a radiation reflectorcomprising a number of panels including a center panel and end panels,and hinged connections joining said panels edge-to-edge on parallelhinge axes; said panels being foldable between a polygonal stowedconfiguration wherein said panels define the sides of a polygon and theouter edges of said end panels are disposed approximately in a planenormal to and bisecting said center panel and containing the axis ofsaid polygon, and a deployed configuration, wherein said panels aredisposed substantially in a common plane; antenna means mounted on theouter sides of said panels; means for rigidly mounting said center panelon the body of said spacecraft; releasable locking means for releasablyjoining said end panel edges in the stowed configuration of said panels;and deployment means for unfolding said panels to their deployedconfiguration upon release of said locking means.
 9. An antennastructure according to claim 8 wherein: said antenna means comprisephased array antenna elemeNts; said locking means comprise explosivelocking means; and said deployment means comprise springs acting betweenthe adjacent reflector panels.
 10. An antenna structure according toclaim 8 wherein: said polygon has an odd number of sides; and said endpanels are disposed at an oblique angle to one another directly oppositesaid center panels in said stowed configuration of said panels to formone apex of said polygon.
 11. An antenna according to claim 8 wherein:said polygon has an even number of sides; each end panel has one-halfthe lateral width of the remaining panels and said end panels aredisposed directly opposite said center panel in a common plane parallelto said center panel in said stowed configuration of said panels so asto form one side of said polygon.